| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.jasper.compiler; |
| |
| import javax.servlet.ServletContext; |
| |
| import org.apache.jasper.JspCompilationContext; |
| |
| /** |
| * Provides {@link ELInterpreter} instances for JSP compilation. |
| * |
| * The search order is as follows: |
| * <ol> |
| * <li>ELInterpreter instance or implementation class name provided as a |
| * ServletContext attribute</li> |
| * <li>Implementation class named in a ServletContext initialisation parameter |
| * </li> |
| * <li>Default implementation</li> |
| * </ol> |
| */ |
| public class ELInterpreterFactory { |
| |
| public static final String EL_INTERPRETER_CLASS_NAME = |
| ELInterpreter.class.getName(); |
| |
| private static final ELInterpreter DEFAULT_INSTANCE = |
| new DefaultELInterpreter(); |
| |
| |
| /** |
| * Obtain the correct EL Interpreter for the given web application. |
| */ |
| public static ELInterpreter getELInterpreter(ServletContext context) |
| throws Exception { |
| |
| ELInterpreter result = null; |
| |
| // Search for an implementation |
| // 1. ServletContext attribute (set by application or cached by a |
| // previous call to this method). |
| Object attribute = context.getAttribute(EL_INTERPRETER_CLASS_NAME); |
| if (attribute instanceof ELInterpreter) { |
| return (ELInterpreter) attribute; |
| } else if (attribute instanceof String) { |
| result = createInstance(context, (String) attribute); |
| } |
| |
| // 2. ServletContext init parameter |
| if (result == null) { |
| String className = |
| context.getInitParameter(EL_INTERPRETER_CLASS_NAME); |
| if (className != null) { |
| result = createInstance(context, className); |
| } |
| } |
| |
| // 3. Default |
| if (result == null) { |
| result = DEFAULT_INSTANCE; |
| } |
| |
| // Cache the result for next time |
| context.setAttribute(EL_INTERPRETER_CLASS_NAME, result); |
| return result; |
| } |
| |
| |
| private static ELInterpreter createInstance(ServletContext context, |
| String className) throws Exception { |
| return (ELInterpreter) context.getClassLoader().loadClass( |
| className).newInstance(); |
| } |
| |
| |
| private ELInterpreterFactory() { |
| // Utility class. Hide default constructor. |
| } |
| |
| |
| public static class DefaultELInterpreter implements ELInterpreter { |
| |
| @Override |
| public String interpreterCall(JspCompilationContext context, |
| boolean isTagFile, String expression, |
| Class<?> expectedType, String fnmapvar) { |
| return JspUtil.interpreterCall(isTagFile, expression, expectedType, |
| fnmapvar); |
| } |
| } |
| } |